Method for the application of reusable fasteners on diapers

ABSTRACT

The invention relates to a method for the application of a reusable fastener, comprising a sealing band and a sealing strip, to a diaper. According to the invention, strips, comprising a support and a backed material with sealing elements in the form of loops or hooks, are fixed to the diaper without adhesive. In a first method step the strips are attached by means of thermobonding or ultrasound welding. In a second methods step, the above are then fixed to the counter-surface by cold pressing or ultrasound welding.

CROSS REFERENCE TO RELATED APPLICATIONS

Applicant claims priority under 35 U.S.C. §119 of German Application No.103 44 536.6 filed Sep. 25, 2003. Applicant also claims priority under35 U.S.C. §365 of PCT/EP2004/010775 filed Sep. 24, 2004. Theinternational application under PCT article 21(2) was not published inEnglish.

The invention relates to a method for affixing a reusable fastener thatconsists of a fastener tape and a fastener strip to a baby diaper,whereby strips that consist of a carrier and a material laminated on,having fastener elements in the form of loops or hooks, are attached tothe baby diaper without adhesive.

The material of the fastener band, i.e. fastener strip that can belaminated on can be produced by means of textile technology. The loopsor hooks, which are produced by means of warp-knitting, for example,interact in the manner of a hook-and-loop system, whereby hook-shapedfastener elements of the one textile material engage into loops of theother textile material. The carrier of the fastener band and/or fastenerstrip can consist of a single-layer or multi-layer film, a textilematerial, or a laminate of a carrier film and a textile materiallaminated onto one side or both sides. Furthermore, the carrier can havea region having differing elasticity in the longitudinal direction ofthe strip. However, it is practical if at least the connection regionsof the carrier, at which the bond with the baby diaper is produced, areconfigured as low-stretch regions. Polyolefins are particularly suitableas materials for the carrier of the fastener band and fastener strip.

Within the framework of the known measures, the fastener bands and thefastener strips are attached to the diaper by means of an adhesive thatis applied to the back of the carrier. Attachment takes place on theouter skin of the diaper, or on a component that is configured as adiaper ear, for example (DE 199 40 185 A1). Handling of materialsprovided with an adhesive makes great demands on processing. Inparticular, it must be assured that the adhesive parts are eithercovered with release films during processing, or only come into contactwith other materials, with the adhesive side, at the desired point intime. Because of these problems, it is proposed in DE 199 52 417 A1 tocoat the strips with a parting layer that contains silicone, on the sideof the fastener elements, which layer must be cured after coating. Thismethod is complicated.

From DE 197 03 557 A1, it is known to attach fastener strips to theoutside of a baby diaper using ultrasound bonding. As anotherpossibility for the production of mechanical bonds, bonding by means ofheat and/or pressure can be considered (EP 0 877 589 B1). Ultrasoundbonding as well as bonding by means of heat and pressure are relativelyslow attachment methods. The required dwell time for the production of afirm bond is clearly longer than the time required for contact gluing.Attachment of a strip forming a reusable fastener to baby diapers bymeans of heat and pressure therefore appears not to be very suitable forpractice, and has not been able to establish itself.

The invention is based on the task of simplifying the attachment of thefastener bands and fastener strips on the baby diaper. The method issupposed to be able to be integrated into the diaper production, and isnot allowed to impair the production speed of the diaper production.

This task is accomplished according to the invention, in the case of themethod described initially, in that the strips are basted on in a firstmethod step, by means of thermobonding or ultrasound bonding, and firmlybonded to the counter-surface in a second method step, by means of coldpressing. The two method steps are carried out in spatially separateworkstations.

In the case of thermobonding, bonding of the materials takes place usinghot tools. In the case of ultrasound bonding, stamping dies thatoscillate at high frequency are used, which produce friction heat. Bymeans of local melting and flow processes, the materials to be bondedare merely fixed in place in a first method step. In a second methodstep, in a spatially separate workstation, the materials aresubsequently firmly bonded by means of cold pressing. In a continuousdiaper production, the two method steps can be carried out at the sametime, in the separate workstations. By dividing the attachment methodinto two method steps, the dwell time that is required for applying andattaching the fastener strips and fastener bands in the case of acontinuous diaper production can be reduced by up to 50%.

According to a preferred embodiment of the invention, the strips are cutfrom a material web, with a cut transverse to the web running direction,and passed to the first workstation by means of a transfer device, inwhich the strips are applied to a web from which the diapers or parts ofthe diapers are produced, and basted on by means of thermobonding orultrasound bonding. A rotating transfer device can be used, inparticular, as the transfer device, which passes the strips to theworkstation with a rotational movement in the same direction as therunning direction of the web. Afterwards, the web is passed through thesecond workstation, in which the strips are firmly bonded to the web.

Using the method according to the invention, bonds between strips anddiapers can be produced, which consist of attachment points disposeddensely next to one another.

In the following, the invention will be explained using a drawing thatpresents an exemplary embodiment merely as an example. The drawingschematically shows:

FIG. 1 a method for affixing a reusable fastener that consists of afastener tape and a fastener strip to a baby diaper,

FIG. 2 the method product produced according to the method described.

In the case of the method shown in FIG. 1, strips 1 are cut from thematerial web 2, with a cut crosswise to the running direction of theweb, and passed to a first workstation 4 by means of a rotating transferdevice 3. The strips 1 cut from the material web 2 consist of a carrierand a material laminated on, having fastener elements in the form ofloops or hooks. In the first workstation 4, they are applied to a web 5from which diapers or parts of diapers are produced, and basted on bymeans of thermobonding or ultrasound bonding. The bond produced in thefirst workstation 4 merely serves to fix the strips 1 in place on asurface that forms the outside of the diaper. Afterwards, the web ispassed through a second workstation 6, in which the strips 1 are firmlybonded to the web 5 by means of cold pressing or ultrasound bonding.

The method product produced according to the method described is shownin FIG. 2. FIG. 2 schematically shows a detail of a baby diaper having alateral fastener band 7, which is attached to a connection region of thediaper configured as a diaper ear 8, and works together with a fastenerstrip disposed on the outside of the diaper, not shown in the figure, asa hook-and-loop fastener. The fastener band 7 consists of a carrier anda material laminated on, having hook-shaped fastener elements that worktogether with loop-shaped fastener elements of the fastener stripattached to the outside of the diaper. The material that is laminated oncan be produced by means of textile technology.

The carrier of the fastener band can consist of a single-layer ormulti-layer film, a textile material, e.g. nonwoven or knitted fabric,or a laminate of a carrier film and a textile material laminated on, onone or both sides. The carrier can have regions having differingelasticity in the longitudinal direction of the strip. Preferably, theconnection region of the carrier that is used for attaching the carrierto the baby diaper is configured as a low-stretch region.

The bond between strip and diaper that is produced according to themethod described above consists of attachment points 9 disposed denselynext to one another, which were produced by means of local meltingand/or flow processes, with the application of pressure.

The fastener strip that consists of a carrier and a material laminatedon, having female fastener elements in the form of loops, is alsoattached to the outside skin of the diaper without adhesive, in themanner described, whereby the fastener strip is only based on, in afirst method step, by means of thermobonding, and is then firmly bondedto the counter-surface in a second method step, by means of coldpressing or ultrasound bonding.

1. Method for affixing a reusable fastener that consists of a fastenertape and a fastener strip to a baby diaper, whereby strips that consistof a carrier and a material laminated on, having fastener elements inthe form of loops or hooks, are cut from a material web with a cutcrosswise to the running direction of the web and passed to a firstworkstation by means of a rotating transfer device, whereby in the firstworkstation the strips are applied without adhesive to a web from whichdiapers or part of diapers are produced and are basted on and merelyfixed in place by means of local melting and flow processes by means ofultrasound bonding, whereby afterwards the web is passed through aspatially separate second workstation, in which the strips are firmlybonded to the web by means of cold pressing.
 2. Method according toclaim 1, wherein the strips are cut from a material web, with a cuttransverse to the web running direction, and passed to the firstworkstation by means of a transfer device, in which the strips areapplied to a web from which the diapers or parts of the diapers areproduced, and basted on by means of thermobonding or ultrasound bonding,and that afterwards, the web is passed through the second workstation,in which the strips are firmly bonded to the web.
 3. Method according toclaim 2, wherein a rotating transfer device is used, which passes thestrips to the workstation with a rotational movement in the samedirection as the running direction of the web.
 4. Method according toclaim 1, wherein a bond is produced between strip and diaper, whichconsists of attachment points disposed densely next to one another.